LOL. before this thread came up I pretty much said what I had to say in the "Ravenlore's Possible Bag" thread:

Also, I have looked at the Gerber with its ability to use small saw blades. IMO those saw blades are much too small to do much real work. Unlike a knife, where a small one can do big work, a saw depends on length to get a good number of teeth across the work. A electrically powered jigsaw can move the tiny blades back and forth a thousand times a minute and get the job done quickly. Using such small blades by hand is pretty miserable about the time you get the blade moving you have to stop and reverse direction.

Even under ideal conditions a 4" saw blade is about the smallest saw blade I consider to be practical to use by hand. The saw blades on my Leatherman are about 2-1/2" and only good at a last resort. Even a 4" blade is pretty much short-stroking it and you end up working mighty hard to get anything done.

Anyone doubting this should try using one of a jigsaw blade to cut through something light, like a softwood 1 by 3 or #3 rebar. These are pretty much the minimum capability in my book. If you can't saw through these in a reasonable amount of time your better off reconsidering your options. A tiny blade will see your arm tired before the job is done. And don't be in a rush.

An 8" or 12" blade is much more useful if your intent is to get something done rapidly.

No matter which saw you use or what your sawing it pays to lubricate the blade with some wax to make it sawing easier. Makes a big difference. Beeswax is perhaps best but a wax candle, perhaps from your fire starting kit, will work.
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I have carried a 'Wood-Zig' pruning saw or a demountable 'Sven saw' if I have reason to believe that I may need a wood saw. One of these bow saws will take any standard 12" hacksaw blade. These blades are kept under tension and are more effective than any 'stab-saw' type blades because they are thinner and are kept straight by being under tension. The only weakness is you need to be able to span what you cut so, unless your really creative and determined, you can't use it in a blind-cut situation.

There are several nice aluminum SawsAll blade holders that will allow you to mount any standard reciprocating saw blade in a comfortable handle. Lennox makes a nice one. You will still have a sore arm trying to do what you can do in a minute with a SawsAll but a longer blade, ideally 12", or a type optimized for the material your cutting is far better than short stroking it with a silly 2" long saber saw blade.